I think sometimes we also forget how young MohUr still are right now...Kastur's just nineteen, and Mohan is just 22! As someone in her mid-twenties right now I can surely say that no one's going to be that mature at that age, no matter how much they want to be: esp when you're expected to marry and support the family...nowadays most people graduate at that age...haven't even stepped into a job yet (unless of course they ended up getting one immediately after their Bachelors). They're stuck in a position they're not emotionally ready to take care of yet...I can't even SAY Kastur is really ready for this because most of her thoughts on marriage are basically her castles in the air. And in Mohan's case it's something that would symbolise being trapped, and I'm sure he would have felt the same way even if the girl was - say for instance - Nikita! They're kids in the marriage brigade, and that's exactly how they are acting!